Double-decker buses will be banned in the next four to five years after an accident in Prachuap Khiri Khan province killed 14 passengers.

The government on Wednesday expressed condolences to the families and friends of the victims involved in the accident, which occurred when a double-decker bus veered off the road and slammed into some trees, resulting in 14 deaths and 32 people injured.

The bus was travelling from Bangkok to Songkhla province. The accident took place in Thap Sakae district in Prachuap Khiri Khan at about 1am on Tuesday.

Rescue workers found 14 bodies at the scene — seven in the upper deck, three in the lower deck and four outside the bus.

The 36-year-old driver is in critical condition in Prachuap Khiri Khan Hospital.

The transport minister has amended a regulation that limits the height of double-decker buses to four metres, down from 4.3 metres now.

The licences of the double-decker buses now on the roads will end in the next 4-5 years and they should be the last of their kind in Thailand, the government said.

The Foundation for Consumers said the crash may have been the result of the driver falling asleep and a lack of maintenance on the vehicle.

The Department of Land Transport said on Wednesday that the bus was travelling at 88 kilometres per hour, which is below the speed limit of 90 km/h.